Conventional centrifugal type pumps comprise an impeller bearing a plurality of vanes. The impeller is rotated about an axis in a chamber having a central inlet and a peripheral outlet for the pumped fluid. While conventional centrifugal type pumps are widely used in industry, the shear forces imparted to the fluid by conventional centrifugal type pumps presents a problem in the case of shear sensitive fluids such as non-Newtonian, thixotropic fluids as well as blood or other biological fluids. While shear forces imparted to the fluid can be reduced by reducing the rotational speed of the impeller's vanes, reducing the rotational speed of the vanes results in a substantial reduction in flow volume and pressure.
It is therefore an object of the present invention to provide a centrifugal type pump for shear sensitive fluids that overcomes the aforesaid and other disadvantages of the prior art. A more specific object of the present invention is to provide a centrifugal type pump characterized by improved volume flow rates with lower fluid shear rates than current centrifugal type pumps.